<div class="panel panel-default">
    <div class="panel-heading">模板内的局部变量</div>
    <div class="panel-body">
      <input #heroInput>
      <p>{{heroInput.value}}</p>
      <button class="btn btn-success" (click)="sayHello(heroInput.value)">局部变量</button>
    </div>
  </div>
